The present invention relates to a laminated band pass filter which is mainly mounted in a high frequency radio device such as a cellular phone, high frequency radio device and laminated bandpass filter manufacturing method.
With miniaturization of communication equipment, a laminated bandpass filter is used in an RF circuit of a cellular phone, etc. in recent years. With reference to the attached drawings, an example of the above-described conventional bandpass filter will be explained.
FIG. 7 shows an exploded perspective view of a conventional laminated bandpass filter and FIG. 8 shows an equivalent circuit diagram of the conventional laminated bandpass filter.
As shown in FIG. 7, the laminated bandpass filter is constructed of dielectric layer 701 to dielectric layer 710 laminated one atop another. An internal grounding electrode 711 is placed on the dielectric layer 701 and capacitor electrodes 712 and 713 are placed on the dielectric layer 702.
Furthermore, strip lines 714 and 715 are placed on the dielectric layer 703 and strip lines 716 and 717 are placed on the dielectric layer 704 and strip lines 718 and 719 are placed on the dielectric layer 705. Capacitor electrodes 720 and 721 are placed on the dielectric layers 706 and 707 respectively and capacitor electrodes 722 and 723 are placed on the dielectric layer 708, and capacitor electrodes 724 and 725 are placed on the dielectric layer 709.
The capacitor electrode 712, one end 718a of the strip line 718 and the capacitor electrode 721 are connected to the capacitor electrode 722 via a via hole 726 and the capacitor electrode 713, one end 719a of the strip line 719 and the capacitor electrode 720 are connected to the capacitor electrode 723 via a via hole 727.
Furthermore, the other end 718b of the strip line 718 is connected to one end 716a of the strip line 716 via a via hole 728 and the other end 719b of the strip line 719 is connected to one end 717a of the strip line 717 via a via hole 729.
Furthermore, the other end 716b of the strip line 716 is connected to one end 714a of the strip line 714 via a via hole 730 and the other end 717b of the strip line 717 is connected to one end 715a of the strip line 715 via a via hole 731. The internal grounding electrode 711 and strip lines 714 and 715 are connected to a grounding electrode 732 formed on the side of the laminated electronic part and the capacitor electrodes 724 and 725 are connected to an input electrode 733 and an output electrode 734 respectively.
An operation of the conventional laminated bandpass filter will be explained shortly using FIG. 7 and FIG. 8. A capacitor C81 is formed between the capacitor electrode 724 and the capacitor electrode 722 and a capacitor C82 is formed between the capacitor electrode 725 and the capacitor electrode 723.
Furthermore, a capacitor C83 is formed between the capacitor electrode 721 and the capacitor electrode 720. Further, capacitors C84 and C85 are formed between the capacitor electrodes 712 and 713 and the internal grounding electrode 711 respectively.
An inductor L81 is formed of the strip lines 718, 716 and 714 and an inductor L82 is formed of the strip lines 719, 717 and 715. The capacitor C81 is connected to the input electrode 733 and the capacitor C82 is connected to the output electrode 734. The capacitor C84 and inductor L81 are connected in parallel with the capacitor C81, the capacitor C83 are connected in series to the capacitor C81, the capacitor C85 and inductor L82 are connected in parallel with the capacitor C82, and the capacitor C83 is connected in series to the capacitor C82, and thereby a two-stage bandpass filter is formed.
However, in the above-described configuration, strip lines exist on multiple layers and resistance components in inductors increase, which reduces a Q value, causing a problem that it is impossible to implement a low loss and sharp bandpass filter used for the RF circuit section. Furthermore, since the strip lines are constructed on multiple layers, there is also a problem that it is difficult to implement a small and low-profile laminated body.
In view of the above-described problems, it is an object of the present invention to provide a small, low-profile and low loss laminated bandpass filter, a high frequency radio device that will realize miniaturization by mounting this laminated bandpass filter and a laminated bandpass filter manufacturing method.
One aspect of the present invention is a laminated bandpass filter comprising:
an input electrode, output electrode and grounding electrode placed on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
an internal grounding electrode provided in an internal layer of said laminated body and connected to said grounding electrode;
a plurality of capacitor electrodes including at least a first and second capacitor electrodes; and
a plurality of strip lines including at least a first and second strip lines,
wherein said first and second capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first and second strip lines, respectively,
the other ends of said first and second strip lines are electrically connected to the grounding electrode, and
said first and second strip lines are placed on said same dielectric sheet in a certain distance and thereby electromagnetically coupled within the same layer.
Another aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines have the same length and width.
Still another aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines are placed in parallel with each other.
Yet still another aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines are electrically connected to said internal grounding electrode via a via hole.
Still yet another aspect of the present invention is the laminated bandpass filter, wherein only said first and second strip lines are placed on said dielectric sheet.
A further aspect of the present invention is a laminated bandpass filter comprising:
an input electrode, output electrode and grounding electrode placed on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
an internal grounding electrode provided in an internal layer of said laminated body and connected to said grounding electrode;
a plurality of capacitor electrodes including at least a first and second capacitor electrodes; and
a plurality of strip lines including at least a first and second strip lines,
wherein said first and second capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first and second strip lines, respectively,
the other ends of said first and second strip lines are electrically connected to the grounding electrode, and
said first strip line is placed on a first dielectric sheet and said second strip line is placed on a second dielectric sheet, and said second dielectric sheet is placed directly below said first dielectric sheet and said first and second strip lines are electromagnetically coupled.
A still further aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines have the same length, width and position within the plane.
A yet further aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines are electrically connected to said internal grounding electrode via a via hole.
A still yet further aspect of the present invention is the laminated bandpass filter, further comprising:
a third capacitor electrode connected to said input electrode;
a fourth capacitor electrode connected to said output electrode;
a fifth capacitor electrode capacitatively coupled with said third capacitor electrode; and
a sixth capacitor electrode capacitatively coupled with said fourth capacitor electrode,
wherein capacitative coupling of an area where said third capacitor electrode and said sixth capacitor electrode overlap each other in the lamination direction forms a jump capacitance.
An additional aspect of the present invention is the laminated bandpass filter, wherein capacitative coupling of an area where said fourth capacitor electrode and said fifth capacitor electrode overlap each other in the lamination direction forms a jump capacitance.
A still additional aspect of the present invention is the laminated bandpass filter, wherein with respect to said grounding electrode, an electrode pattern of at least one of said first and second capacitor electrodes is laminated, an electrode pattern of at least one of said first and second strip lines is laminated on a layer superior thereto, and an electrode pattern of at least one of the capacitor electrode connected to said input electrode and the capacitor electrode connected to said output electrode is laminated on a layer superior to said layer.
A yet additional aspect of the present invention is the laminated bandpass filter, wherein all electrode patterns constituting the capacitor electrode connected to said input electrode and the capacitor electrode connected to said output electrode as an input/output capacitance are provided on a layer superior to the layer constituting said strip lines.
A still yet additional aspect of the present invention is the laminated bandpass filter, wherein with respect to said grounding electrode, an electrode pattern of at least one of said first and second capacitor electrodes is laminated, an electrode pattern of at least one of said first and second strip lines is laminated on a layer superior thereto, and an electrode pattern of at least one of said third to sixth capacitor electrodes is laminated on a layer superior to said layer.
A supplementary aspect of the present invention is the laminated bandpass filter, wherein said third to sixth capacitor electrodes are provided on a layer superior to the layer constituting said strip lines.
A still supplementary aspect of the present invention is a laminated bandpass filter comprising:
an input electrode, output electrode and grounding electrode placed on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
an internal grounding electrode provided in an internal layer of said laminated body and connected to said grounding electrode;
a plurality of capacitor electrodes including at least a first to fourth capacitor electrodes; and
a plurality of strip lines including at least first to fourth strip lines,
wherein said first to fourth capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first to fourth strip lines, respectively,
the other ends of said first to fourth strip lines are electrically connected to the grounding electrode, and
said first and second strip lines are placed on said first dielectric sheet in a certain distance, said first and second strip lines are electromagnetically coupled within the same layer, said third and fourth strip lines are placed on the second dielectric sheet in a certain distance, said third and fourth strip lines are electromagnetically coupled within the same layer, said second dielectric sheet is placed directly below said first dielectric sheet and said first and third strip lines and said second and fourth strip lines are electromagnetically coupled respectively.
A yet supplementary aspect of the present invention is the laminated bandpass filter, wherein said first to fourth strip lines have the same length and width, said first and third strip lines have the same position within the plane and said second and fourth strip lines have the same position within the plane.
A still yet supplementary aspect of the present invention is the laminated bandpass filter, wherein said first and second strip lines are placed in parallel with each other and said third and fourth strip lines are placed in parallel with each other.
Another aspect of the present invention is the laminated bandpass filter, wherein said first to fourth strip lines are connected to said internal grounding electrode via a via hole.
Still another aspect of the present invention is the laminated bandpass filter, further comprising:
a fifth capacitor electrode connected to said input electrode;
a sixth capacitor electrode connected to said output electrode;
said seventh capacitor electrode capacitatively coupled with said fifth capacitor electrode; and
said eighth capacitor electrode capacitatively coupled with said sixth capacitor electrode,
wherein capacitative coupling of an area where said fifth capacitor electrode and said eighth capacitor electrode overlap each other in the lamination direction forms a jump capacitance.
Yet still another aspect of the present invention is the laminated bandpass filter, wherein capacitative coupling of an area where said sixth capacitor electrode and said seventh capacitor electrode overlap each other in the lamination direction forms a jump capacitance.
Still yet another aspect of the present invention is the laminated bandpass filter, wherein said dielectric sheet is made up of a crystal phase and a glass phase, said crystal phase includes at least one of Al2O3, MgO, SiO3 and ROa where R is at least one element selected from La, Ce, Pr, Nd, Sm and Gd and a is a numerical value determined stoichiometrically according to the valence of said R.
A further aspect of the present invention is a laminated bandpass filter, said laminated body incorporating the bandpass filter and the bandpass filter.
A still further aspect of the present invention is a composite high frequency device, wherein said laminated body incorporates the bandpass filter and another high frequency circuit.
A yet further aspect of the present invention is a composite high frequency device, wherein electronic parts are mounted on said laminated body incorporating the bandpass filter.
A still yet further aspect of the present invention is a high frequency device, characterized by comprising the laminated bandpass filter.
An additional aspect of the present invention is a laminated bandpass filter manufacturing method comprising the steps of:
forming an input electrode, output electrode and grounding electrode on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
forming an internal grounding electrode in an internal layer of said laminated body connected to said grounding electrode;
forming a plurality of capacitor electrodes including at least a first and second capacitor electrodes; and
forming a plurality of strip lines including at least a first and second strip lines,
wherein said first and second capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first and second strip lines, respectively,
the other ends of said first and second strip lines are electrically connected to the grounding electrode, and
said first and second strip lines are placed on said same dielectric sheet in a certain distance and thereby electromagnetically coupled within the same layer.
A still additional aspect of the present invention is a laminated bandpass filter manufacturing method comprising the steps of:
forming an input electrode, output electrode and grounding electrode on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
forming an internal grounding electrode in an internal layer of said laminated body connected to said grounding electrode;
forming a plurality of capacitor electrodes including at least a first and second capacitor electrodes; and
forming a plurality of strip lines including at least a first and second strip lines,
wherein said first and second capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first and second strip lines, respectively,
the other ends of said first and second strip lines are electrically connected to the grounding electrode, and
said first strip line is placed on a first dielectric sheet,
said second strip line is placed on a second dielectric sheet, and
said second dielectric sheet is placed directly below said first dielectric sheet and thereby said first and second strip liens are electromagnetically coupled.
A yet additional aspect of the present invention is a laminated bandpass filter manufacturing method comprising the steps of:
forming an input electrode, output electrode and grounding electrode on an end face of a laminated body integrating a plurality of laminated dielectric sheets;
forming an internal grounding electrode in an internal layer of said laminated body connected to said grounding electrode;
forming a plurality of capacitor electrodes including at least a first to fourth capacitor electrodes; and
forming a plurality of strip lines including at least first to fourth strip lines,
wherein said first to fourth capacitor electrodes are capacitatively coupled with said internal grounding electrode and electrically connected to one ends of said first to fourth strip lines, respectively,
the other ends of said first to fourth strip lines are electrically connected to the grounding electrode, and
said first and second strip lines are placed on said first dielectric sheet in a certain distance, said first and second strip lines are electromagnetically coupled within the same layer,
said third and fourth strip lines are placed on said second dielectric sheet in a certain distance, said third and fourth strip lines are electromagnetically coupled within the same layer,
said second dielectric sheet is placed directly below said first dielectric sheet and said first and third strip lines and said second and fourth strip lines are electromagnetically coupled respectively.